This article describes a specific instrument for detection of excitation winding shorted turns in hydro generators, developed in Koncar - Electrical Engineering Institute Inc., called Hydro generator Winding Fault Detection (HO WFD). This instrument is a part of the Institute's product line used for monitoring and diagnosis of rotating electrical machines.
A key issue in the operation of all machines is its proper and reliable work, which in economic terms means to achieve the maximum financial benefit and to stay within technical constraints. Therefore, the reduction of unplanned downtime and unnecessary maintenance is very important, and detection of machine failure conditions is of the utmost importance if we want to achieve better asset management. The main goal of each detection method is early and accurate failure detection, which allows the fault to be eliminated before it causes major damage.
One of the common failures that can occur in hydro generators is excitation winding shorted turn. Short circuits are the result of failure of the winding insulation between individual turns, and by aging of the isolation they become more likely and more frequent. Impact on the generator, if it works with short circuited tums, ranges from practically no influence on the operation of the machine, to the occurrence of expressed vibrations, load limits, high operating temperatures and forced outages. The magnitude of the effect to the machine working with short-circuited turns, depends on the location and number of turns that are shorted.